Place a large rimless baking sheet or an inverted rimmed baking sheet in the oven and heat to 450 degrees.

Whisk flour, salt, baking powder, rosemary and black pepper together in a large bowl. With a wooden spoon, stir in the water and olive oil until a medium stiff dough forms. Knead gently if necessary to combine. Let rest in the bowl covered with a plate or plastic wrap for 30 minutes.

Divide dough into 6 to 8 portions, depending on the size of your cookie sheet. One at a time, roll dough out with lots of flour into a paper-thin rustic round; the thinner you roll it, the thinner the cracker will be. Experiment to find just the thickness that suits you.

Place on the parchment paper and brush excess flour off the dough, then brush liberally with olive oil and sprinkle with a little sea salt. With another cookie sheet or pizza peel, transfer to the hot baking sheet and bake for 8 to 12 minutes until lightly browned on the edges with specks of brown throughout. Remove from the oven, cool and break into large pieces. Repeat with the remaining dough.